The present invention relates to an optical disk apparatus which reads data recorded on an optical disk or writes data on the optical disk and an objective lens driving apparatus used for the optical disk apparatus.
An optical disk apparatus performs high-speed data recording/playback by rotating an optical disk at high speed. An objective lens follows high-speed rotation of the optical disk and moves at high speed. For this reason, the movable part of an objective lens driving apparatus needs to increase the thrust per unit mass. High-speed rotation of an optical disk causes a rise in servo band. When the servo band rises, the resonance frequency of the movable part must be increased. JP-A-2002-312961 (pp. 2 to 5 and FIG. 1) describes an objective lens actuator which copes with an increase in resonance frequency of a movable part. In this publication, a protruding part is provided to the lens holder of the objective lens actuator, thereby increasing the rigidity of the movable part.
The objective lens actuator described in JP-A-2002-312961 achieves an increase in rigidity of the movable part. However, the protruding part increases the mass of the movable part. As a result, it is difficult to increase the thrust per unit mass of the objective lens driving apparatus required to record/play back data at high speed.